516 
NATURE 
[ Oct. 26, 1871 

falling and despairing, a helper and encourager of the useful and 
active ; and she may be all this and more in a manner which no 
man, however able or gified, can fully or effectually imntate. 
But to secure such fruits as these, she must have sown abund- 
antly the good seed of mental and moral discipline in the sunny 
spring time of youh. Lastly, with reference to this branch of 
the subject, it may be maintained that liberal culture will fit a 
woman better even for the ordinary toils and responsibilities of 
household life. Even a domestic servant is of more value to her 
employer if sufficiently intelligent to understand the use and 
meaning of her work, to observe and reason about the best 
mode of arranging and managing it, to be thoughtful and careful 
with reference to the things committed to her charge. How 
much more does this apply to the head of the house, who, in 
the daily provisioning and clothing of her little household army, 
the care of their health, comfort, occupations and amusements, 
the due and orderly subordination of ‘he duties and interests of 
servants, children, and friends, and the arrangement of the thou- 
sand difficulties and interferences that occur in these relations, 
has surely much need of sys'em, tact, information, and clearness 
of thought. We realise the demands of her position only when 
we consider that she has to deal with all interests from the 
commonest to the highest, with all classes of minds from the 
youngest and most untutored to the most cultivated; and that 
she may be required at a moment’s notice to divert her thoughts 
from the gravest and most serious concerns to the most trifling 
details, or to emerge from the practical performance of the most 
commonplace duties into the atmosphere of refined and culti- 
vated society. But it would be altogether unfair to omit the consi- 
deration of still another aspect of this matter. Woman has 
surely the right to be happy as well as useful, and should have 
fully opened to her that exalted pleasure which arises from the 
development of the mind, from the exploration of new regions 
of thought, and from an enlarged acquaintance with the works 
and ways of God, The man who has enjoyed the gratification 
of exercising his mental powers in the fields of scientific inves- 
tigation or literary study—of gathering their flowers and gems, 
and of breathing their pure ard bracing atmosphere, would 
surely not close the avenues to such high enjoyment against 
woman. The desire to do so would be an evidence of sheer 
pedantry or moral obliquity, of which any man should be 
ashamed. On the contrary, every educated man and woman 
should in this respect be an educational miss onary, most de 
sirous that others should enjoy these pleasures and privileges, 
both as a means of happiness and as a most effectual preventive 
of low and pernicious tastes and pursuits. 

RECENT RESEARCHES ON FLIGHT* 
OF late the perplexing problem of flight has received a greater 
amount of attention from physiologists and savants than 
has been bestowed upon it for years, and the result of their 
researches and experiences is in a fair way of becoming remark- 
able for its fruit-bearing character. Whilst abroad, such men as 
Borelli, Straus-Durckheim, Chabrier, Girard, and Marey, have 
severally given to the world the gist of their labours in this 
branch oi science; at home, the Duke of Argyll and Dr. J. 
Bell Pettigrew have awakened our deep interest by their 
views on natural and artificial flight. To the latter is due the 
honour of giving birth to the celebrated “ figure-of-8 wave 
theory,” that is now attracting so much notice in our aeronautical 
schools. 
As early as 1867, Dr. Pettigrew delivered. before the Royal 
Institution of Great Britain, a lecture, in which he propounded 
that novel theory, and in 1868 he published in the ‘‘ Trans- 
actions” of the Linnean Suciety an elaborate memoir on ‘ The 
Mechanical Appliances by which Flight is attamed in the 
Animal Kingdom.” The year after, Prof. J. E. Marey, in the 
** Revue des Cours Scientifi ues,” bore out Dr. Petuyrew’s ideas, 
by the detaii of his experiments with the sphygmograph, with 
which he succeeded in causing the wings of insects and birds to 
regisier theirown movements. Hesays :—‘‘ Butif the frequency 
of the movements of the wing vary, the form does not vary. It 
is invariably the same ; it is always a double loop, a ficure of 8. 
Wheiher this figure be more or less apparent, whether is 
branches be more or Jess equal, matters litle: it exists and an 
attentive examimation will not fail to reveal it.” An inde- 
fatigable worker, Dr. Pettigrew continued, without pausing, the 
task to which he had set himself—and that to him is indeed a 
* Communicated by the Author from Land and Water. 

labour of love ; and in this year’s ‘‘ Transactions” of the Royal 
Society of Edinburgh, we have from his pen a complete mono- 
graph on ‘* The Physiology of Wings,” in which he treats with 
equal felicity of both navural and artificial flight. The mass of 
interesting faci brought to light by the author is too copious to 
allow of lengthened discussion, but from it we abstract the 
following items :— 
“‘The wing is generally triangular in form. It is finely 
graduated, and tapers from the root towards the tip. It is like- 
wise slightly twisted upon itself, and this remark holds true also 
of the primary or rowing feathers of the wing of the bird. The 
wing is convex above and concave below ; this shape, and the 
fact that in flight the wing is carried obliquely forward like a 
kite, enabling it to penetrate the air with its dorsal surface 
during the up stroke, and to seize it with its ventral one alike 
during the down and up strokes. The wing is moveable in all 
its parts; it is also elastic. Its power of changing form enables 
it to be wielded intelligently, even to its extremity ; its elasticity 
prevents shock, and contributes to its continued play. The wing 
of the insect is usually in one piece, that of the bat and bird 
always in several. The curtain of the wing is continuous in the 
bat, because of a delicate elastic membrane which extends be- 
tween the fingers of the hand and along the arm; that of the 
bird is non-continuous, owing to the presence of feathers, which 
open and close like so many valves during the up and down 
strokes, 
‘The posterior margin of the wing of the insect, bat, and 
bird, is rotated downwards and forwards during extension, and 
upwards and backwards during flexion. The wing during its 
vibration cescends further below the body than it rises above it. 
This is necessary for elevating purposes. The distal portion of 
the wing is twisted in a downward and forward direction at the 
end of the down stroke, whereas at the end of the up stroke it 
is twisted downwards and backwards. The wing during its 
vibrations twists and untwists, so that it acts as a reversing re- 
ciprocating screw. The wing is consequently a screw, struc- 
turally and functionally. The blur or impression produced on 
the eye by the rapidly oscillating wing is twist-d upon itself, and 
resembles the blade of an ordinary screw-propeller. The twisted 
configuration of the wing and iis screwing action are due to the 
presence of figure-of-8 looped curves on its anterior and posterior 
margins ; the curves, when the wing is vibrating, reversing and 
reciprocating in such a manner as to make the wing change form 
in all its parts.” 
We may further point out that Dr. Pettigrew has not based 
his ideas on the structure of wings on mere theoretical considera- 
tions. Besides elaborate anatomical examination, he has entered 
with a true experimental spirit into a close study of the visible 
movements of most of the winged tribe. The very excellent 
diagramatic views with which his paper is elaborately illustrated 
convey at a glance much that it is difficult to express in words. 
In proof of this the reader need but compare those figures bear- 
ing on the wing movements of the butterfly, the dragon-fly, and 
the bird. 
On these and similar deductions from the practical study of 
natural history, Dr. Pettigrew bases his elements of artificial 
flight. J. MuriE 

INSTRUCTIONS FOR OBSERVERS, AT THE 
ENGLISH GOVERNMENT ECLIPSE EXPE- 
DITION, 1871 
SPECI ROSCOPIC OBSERVATIONS 
THE instruments used should, if possible, be of the following 
forms ; and experience has sown that they should all be 
equatorially mounted and driven by clockwork (l of course 
excepte ) :— 
Justrument A,—An analysing spectroscope showing the whole 
spectrum in one field, with reference spectra, or some means of 
rapid record, and with long slit ana long collimator mounted at 
right angles to the axis of a reflecting telescope of Jarge aperture 
and short focal length, with la-ge finder, the slit of the spectro- 
scope, of course, lying in the focus of thespeculum. This com- 
bination enabies us to obtain a'smail bright image of the corona, 
and by throwing this small imaye on the long slit, to cbserve the 
spectrum of the corona on both sides the dark moon—the long 
collimator permitting the slit to be as wide as possible, so that 
the maximum of light is admitted. The prism throwing the 
1eference-spectrum into the collimator slides along a bar, so that 
the reference-spectrum may be made to occupy any part of the 
